Nameplate on the electric Motor
UNIT 3 ELECTRIC MOTORS
Electric Motors are a key element in many electrical systems. A
sudden failure of an electric motor may lead to cost expensive
downtime, damage to surrounding equipment or even to put in
danger Vessel’s safety.
All motorsare crucial for safe operation of the vessel and in
order to reassure safe voyages, motors have to be maintained
strictly.
What is electric motor?
An electric motor is an electric machine that converts electrical energy
into mechanical energy.
Working principle
In normal motoring mode most electric motors operate through the
interaction between an electric motor’s magnetic field and winding
currents to generate force within the motor.
Motor Construction
Rotor
The rotor is the rotating electrical component. It consists of a group of
electro-magnets arranged around a cylinder, with the poles facing
toward the stator poles. The rotor is located inside the stator and is
mounted on the AC motor's shaft. The interact with the magnetic filed
of the stator generates the forces that turn the shaft.
Stator
The stator is in the stationary electrical component. It consists of a
group of individual electro-magnets arranged in such a way that they
form a cylinder, with one pole of each magnet facing toward the center
of the group
Windings
Windings are wires that are laid in coils, usually wrapped around a
laminated soft iron magnetic core to form magnetic poles when
energized with current.
Air Gap
In between the rotor and stator is the Air Gap. The Air Gap has
important effects and is generally as small as possible, as a large gap
has strong negative effect on the performance of an electric motor.
Commutator
A Commutator is a mechanism used to switch the input of certain AC
and DC machines consisting of slip ring segments insulated from each
other and from the electric motor’s shaft. The motor’s armature current
supplied through the stationary brushes in contact with the revolving
commutator which causes required current reversal and applies power
to machine in an optimal manner as the rotor rotates from pole to pole.
AC Electric Motor General View
DC ElectricMotorGeneralView
Types of electric Motors
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Advantages of Induction Motors
• Low cost: Induction motor are very cheap when compared to
synchronous and DC motors. This is due to the modest design of
induction motor.
• Low maintenance cost: The construction of induction motor is very
simple and hence maintenance is also easy, resulting in low
maintenance cost.
• Easy operation: Operation of induction motor is very simple because
there is no electrical connector to the rotor that supply power and
current is induced. Induction motors are self start motors.
• Speed Variation: The speed variation of induction motor is nearly
constant. The speed typically varies only by a few percent going from
no load to rated load.
• High starting torque: The staring torque of induction motor is very
high which makes motor useful for operations where load is applied
before the starting of the motor.
Task 1 Construction of a motor (choose the correct answer)
1. It consists of a group of electro-magnets arranged around a cylinder, with the poles facing toward the stator poles.
- Rotor
- Stator
- Commutator
2. It consists of a group of individual electro-magnets arranged in such a way that they form a cylinder, with one pole of each magnet facing toward the center of the group
- Rotor
- Stator
- Commutator
3. wires that are laid in coils
- cable
- winch
- winding
4. In between the rotor and stator is
- Commutator
- Shaft
- Air gap
5. a mechanism used to switch the input of certain AC and DC machines consisting of slip ring segments insulated from each other and from the electric motor’s shaft.
- Commutator
- Rotor
- Stator
6. Provides cooling
- Frame
- Air gap
- Fan
7. Provides necessary information about the motor
- Frame
- Nameplate
- Painting
8. suitable for connecting wires
- frame
- bolt
- terminal box
9. Rotating machine element used to transmit power
- Frame
- Shaft
- Fan
10. Cover for bearings
- end shield
- hatch cover
- port hole
Task 2Nameplate on the electric Motor (matching)
The nameplate is a metal or other durable tag or label that is affixed to
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the outside of motor housing called Frame. Important information about
the motor is on the label, without it, it will be difficult to determine its
suitability to a task. Typical information found on most motors include:
Manufacture’s Name
Model and Serial No
Rpm
Horsepower
Voltage
Current
Wiring Diagram
Frame Style
Type
Frequency
A. How to connect terminals for different voltages, speeds anddirection of rotation
B. How much work it can perform
C. Rated frequency is the frequency the motor is designed to work inits full potential.
D. Amperage requirements
E. The number of revolutions the rotor makes in one minute
F. The name of the Company that made the motor
G. Information that identifies your particular motor
H. Voltage and phase requirements
I. Physical dimensions and mounting pattern
J. Describes if frame is open, total enclosed fan cooled, etc.
Nameplate on the electric Motor
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